1. Field of the Invention
The present invention relates to an electron-beam projection lithography system. More particularly, the present invention relates to an emitter for an electron-beam projection lithography system, the emitter being capable of emitting electrons only from a selected portion thereof, a manufacturing method thereof, and a method of operating the emitter.
2. Description of the Related Art
In semiconductor manufacturing processes, a variety of lithography systems are used for processing a surface of a substrate into a desired pattern. Optical lithography systems using visible light have been widely employed, but these systems are limited in how narrow a line width they can realize. Accordingly, a next generation lithography (NGL) system, which allows a more finely integrated semiconductor integration circuit with a line width of on the order of nanometers to be realized, has been recently proposed. The NGL system can be divided into an electron-beam projection lithography (EPL) system, an ion projection lithography (IPL) system, an extreme ultraviolet lithography (EUVL) system, a proximity X-ray lithography (PXL) system, as well as others.
The EPL system uses an electron-beam to pattern an electron-resist coated on a subject substrate. An electron beam emitter used in the EPL system can be easily realized, and the construction of the emitter is relatively simple.
In FIG. 1, a cross-sectional view of a conventional electron-beam projection lithography emitter is illustrated. Referring to FIG. 1, an electron-beam projection lithography emitter 10 has a structure where an insulating layer 12 and a gate electrode layer 13 are sequentially stacked on a silicon substrate 11. The insulating layer 12 is formed of a silicon oxide film, and the gate electrode layer 13 is formed of a conductive metal such as aluminum (Al).
The insulating layer 12 of the emitter 10 is patterned into a predetermined pattern including a thin portion and a thick portion. When a voltage is applied between the silicon substrate 11 and the gate electrode layer 13, electrons are emitted through the thin portion of the insulating layer 12 from the silicon substrate 11. The emitted electrons collide with an electron-resist coated on an object substrate to be processed (not shown), facing a top surface of the emitter 10. As a result, the electron-resist is patterned in the same pattern as that of the insulating layer 12.
As described above, since the electrons are emitted through an entire area, the pattern image formed on the emitter 10 is projected onto the object substrate to be processed. Then, after the first patterning throughout the entire area, there may be a need to repair or further pattern a portion of the patterned electron-resist. However, the conventional emitter 10 does not permit such partial electron emission.